package com.hmdp.utils;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.hmdp.entity.Shop;
import lombok.extern.slf4j.Slf4j;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Service;

import java.time.LocalDateTime;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;

import static com.hmdp.utils.RedisConstants.CACHE_SHOP_KEY;
import static com.hmdp.utils.RedisConstants.CACHE_SHOP_TTL;

@Component
@Slf4j
public class CacheClient {

    private final StringRedisTemplate stringRedisTemplate;


    public CacheClient(StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
    }

    public void set(String key, Object value, long time, TimeUnit  unit){
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(value),time,unit);
    }
    public void setWithLogicalExpire(String key, Object value, long time, TimeUnit  unit){
        //设置逻辑过期
        RedisData redisData = new RedisData();
        redisData.setData(value);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(unit.toSeconds( time)));

        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(redisData));
    }
    public <R,ID> R queryWithPassThrough(String keyPrefix, ID id, Class<R> type, Function<ID,R> dbFallback, long time, TimeUnit  unit) {
        String key = keyPrefix + id;
        //从redis中查商铺
        String Json = stringRedisTemplate.opsForValue().get(key);
        if (StrUtil.isNotBlank(Json)){
            return JSONUtil.toBean(Json, type);
        }
        if (Json != null){
            return null;
        }

        R r = dbFallback.apply( id);

        if (r == null){
            stringRedisTemplate.opsForValue().set(key,"",2, TimeUnit.MINUTES);

            return null;
        }
        this.set(key, r, time, unit);


        return r;
    }
    private static  final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);
    public <R,ID> R queryWithLogicalExpire(String keyPrefix, ID id, Class<R> type, Function<ID,R> dbFallback, long time, TimeUnit unit) {
        //从redis中查商铺
        String key = keyPrefix + id;
        String Json = stringRedisTemplate.opsForValue().get(key);
        if (StrUtil.isBlank(Json)){
            return null;
        }
        //命中，需要判断过期时间，先反序列化为对象
        RedisData redisData = JSONUtil.toBean(Json, RedisData.class);
        JSONObject data =(JSONObject) redisData.getData();
        R r = JSONUtil.toBean(data, type);
        LocalDateTime expireTime = redisData.getExpireTime();
        //判断是否过期，未过期则返回商铺信息
        if (expireTime.isAfter(LocalDateTime.now())){
            return r;
        }
        //已过期，需要缓存重建
        //获取互斥锁
        String lockKey = "lock:shop:" + id;
        boolean isLock =  trylock(lockKey);
        if (isLock){
            CACHE_REBUILD_EXECUTOR.submit(() -> {
                try {
                    R r1 = dbFallback.apply(id);
                    this.setWithLogicalExpire(key, r1, time, unit);

                } catch (Exception e) {
                    throw new RuntimeException(e);
                } finally {
                    unLock(lockKey);
                }
            });

        }

        //成功则开启独立线程开启缓存重建

        //返回过期的商铺信息

        return r;
    }





    private boolean trylock(String Key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(Key,"1",10,TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }
    private void unLock(String Key){
        stringRedisTemplate.delete(Key);
    }
}
